Today i started using an awesome application called f.lux.It makes the color of your computer's display adapt to the time of day, warm at night and like sunlight during the day.F.lux has linux, windows and mac binaries.But at the time being, linux binary does not have any gui, it is cli only.(Indeed it does not matter, it is so easy to use.And yes that image is not from linux binary XD )Here is how to get it working under ubuntu/linux :